Apparatus for alternating air-pressures.



UNITED STATES PATENT OFFICE.

HENRY FORCE GAREY, OF BALTIMORE, MARYLAND.

APPARATUS FOR ALTERNATING AlR-PRESSURES.

SPECIFICATION forming part of Letters Patent No. 715,732, dated December 9, 1902.

Application filed March 20, 1902. Serial No. 99,137. (No model.)

To all whom it may concern.-

' ing the eye or other portion of the body and involves devices for rapidly alternating in an inclosed space normal atmospheric pressure and a pressure difiering from such normal pressure.

One of many embodiments of the invention is illustrated in the accompanying drawings, in which- Figure 1 is a plan view of the apparatus; Fig. 2, a side elevation; Fig. 3, a detail section; Fig. 4, a face view of a crank-plate, and Fig. 5 an edge view of the devices of Fig. 4:.

In the figures, A designates a frame supporting a cylinder B, in which is a plunger 0, operated by a plunger-rod O pitman J, crank-pin I, crank-plate I, and shaft D, the latter rotated in any convenient manner, as by pulleys H or a handcrank G, acting through friction-wheels E F. The crank-pin is adjustable in distance from the shaft and also from side to side of the latter by means of a screw K K. From the forward end of the cylinder a passage leads through a pipe N and a block L to the surface of the shaft D, upon which the accurately-fitting block is pressed by a spring M. Beneath the block and in the plane of" the end of the passage the shaft is provided with a peripheral groove 0 of such extent that during alternate strokes of the plunger the passage communicates through the groove with the open air, while during the intermediate and contrary strokes the body of the shaft closes the passage. If the adjustment is such that the passage is closed while the plunger is making a forward stroke, the passage will necessarily be open during the contrary stroke, and continued rotation of the shaft in the same direction will result in a series of compressions in the cylinder alternating with periods of normal or atmospheric pressure, and this will continuebe closed by pressure against any body to which it may be desired to impart the vibrations of the air within the cylinder. For example, the pipe or any suitable extension thereof may be pressed upon parts surrounding the eye.

It is obvious that the passage leading from the cylinder to the shaft is not necessarily in a pipe distinct from. the frame, nor the block necessarily distinct from the bearings of the shaft, nor non-integral with the pipe, nor held against the shaft by the means shown, and that in various other ways the construction might be varied without passing beyond the proper limits of my invention.

What I claim is- The combination with the cylinder and plunger therein, of the rotary shaft carrying 

